Orthodontic device

ABSTRACT

An orthodontic device includes a generally U-shaped metal wire whose two ends are at different vertical heights and which therefore has a 3-dimensional recumbent S shape in front view. The U-shaped metal wire is secured, by an elastic band or a cover, to each of a plurality of orthodontic brackets cemented respectively to a patient&#39;s teeth, and due to the difference of height between the two ends of the U-shaped metal wire, a resilient restoring force is generated to individually adjust the row of teeth on the upper or lower jaw to the normal heights and thereby correct the occlusal cant and craniofacial anomalies.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to orthodontic devices and, moreparticularly, to an orthodontic device capable of individually adjustingthe row of teeth on the upper or lower jaw to the normal tooth positionsby means of a resilient restoring force resulting from a heightdifference between the two ends of a U-shaped metal wire.

2. Description of the Prior Art

Orthodontics is a branch of dentistry that provides a variety oftreatments for people who suffer from malocclusion or who are notsatisfied with their looks because of tooth irregularity,disproportionate jaw relationships, or both. Malocclusion may resultfrom congenital maxillary/mandibular hyperplasia or hypoplasia, toothabnormalities, or a size mismatch between the teeth and the dentalarches. The various conditions of malocclusion include crowding ofteeth, crossbite, forward or backward projection of teeth, excessivespacing between teeth, tooth impaction, misalignment of teeth due tocongenitally missing teeth or supernumerary teeth, and so on. Bad oralhabits may also lead to such malocclusion problems as openbite,crossbite, and a narrow upper dental arch.

Therefore, orthodontic devices are designed to improve the abnormaldevelopment of facial bones, rearrange misaligned teeth, and therebyachieve the following therapeutic purposes:

1. To restore mastication function and thereby improve digestion and theabsorption of nutrients;

2. To facilitate the maintenance of oral hygiene and thereby preventtooth decay and periodontal diseases;

3. To enhance facial esthetics for higher self-confidence and therebypromote normal character development;

4. To enable correct pronunciation and thereby increase learningefficiency; and

5. To enable proper occlusion and lip closure, thereby preventingdryness of the oral mucosa and enhancing the resistance of the oralcavity against infection.

Orthodontic treatments are generally classified as follows, according tothe orthodontic appliances used:

1. Fixed orthodontic brackets: According to the patient's liking,orthodontic brackets made of metal, transparent ceramics, or compoundsare cemented to the outer or inner sides of the patient's teeth by anadhesive and serve as a medium for delivering force to the teeth.

2. Removable orthodontic devices: Orthodontic plates are placed in thepatient's mouth and can be easily removed for easy maintenance of oralhygiene.

3. Jaw bone correction appliances:

(1) An extraoral traction appliance is worn on the patient's head togenerate a traction force that influences bone growth.

(2) An intraoral functional orthodontic appliance uses the patient'smuscles and biting action to generate an orthodontic force thatinfluences the development of the lower face.

A conventional fixed orthodontic device typically includes a straightorthodontic wire fixed in position by rubber bands to a plurality oforthodontic brackets cemented to the tooth surfaces. Each end of theorthodontic wire is attached via a spring to an orthodontic screwimplanted in the alveolar bone, so as for the springs to exert a pullingforce and thereby pull the skew or misaligned teeth to the normalpositions, with a view to correcting jaw position. However, such aconventional orthodontic device is applicable only to horizontaladjustment (e.g., the correction of crowded teeth, forward- orbackward-projecting teeth, excessive spacing between teeth, congenitallymissing teeth, etc.) but is not suitable for adjusting an inclined rowof teeth caused by a vertically tilting upper or lower jaw.

Besides, installation of the conventional fixed orthodontic devicesinvolves local anesthesia and implantation of orthodontic screws intothe alveolar bone where the tooth roots are not located. Moreover, thesprings which are used to tighten the orthodontic wire do not havedirect corrective effect on the jaw bone. Hence, not only are theinstallation and removal of the orthodontic devices complicated, butalso the patients will have to endure pain and discomfort during theinstallation and removal processes.

SUMMARY OF INVENTION

The primary objective of the present invention is to provide anorthodontic device for adjusting a patient's teeth to positions capableof normal occlusion, wherein the adjustment is carried out by means of aresilient restoring force generated by a U-shaped metal wire whose twoends have a height difference. Thus, fast, effective, and painlesscraniofacial correction can be achieved without having to implant screwsinto the patient's jaw bone.

In order to achieve aforementioned objective, the present inventiondiscloses an orthodontic device which comprises a U-shaped metal wireconfigured to be installed on a plurality of orthodontic bracketscemented to a row of teeth. The U-shaped metal wire has a left end and aright end located at different vertical heights with respect to ahorizontal plane passing lengthwise through the U-shaped metal wire at amiddle point thereof. Wherein, after the U-shaped metal wire isinstalled on the plural orthodontic brackets cemented to the row ofteeth, the left and right ends of the U-shaped metal wire are pressedvertically to generate a resilient restoring force for pushing andpulling the row of teeth on an upper jaw or a lower jaw and therebyadjusting the teeth from an inclined alignment to a horizontalalignment.

In a preferred embodiment, the U-shaped metal wire is made of aresilient metallic material, the resilient metallic material being oneof stainless steel, iron, titanium, β-titanium, nickel titanium, clearmaterial and a shape memory alloy.

In a preferred embodiment, the greater a vertical distance between theleft and right ends of the U-shaped metal wire is, the stronger theresilient restoring force of the U-shaped metal wire will be, and theharder the left and right ends of the U-shaped metal wire will springback in two opposite directions respectively.

In a preferred embodiment, the U-shaped metal wire and the pluralorthodontic brackets on which the U-shaped metal wire is installed areprovided on one of outer surfaces and lingual surfaces of the row ofteeth.

In a preferred embodiment, the U-shaped metal wire is fixed in positionto the plural orthodontic brackets by one of the following: a pluralityof rubber bands and a plurality of covers of self-ligation brackets.

In a preferred embodiment, the orthodontic brackets are one of metalorthodontic brackets, ceramic orthodontic brackets, crystal orthodonticbrackets, self-ligation brackets and lingual orthodontic brackets, thelingual orthodontic brackets being cemented to the lingual surfaces ofthe teeth.

In a preferred embodiment, the U-shaped metal wire has a rectangularcross-section and is twisted continuously in the same direction,starting from the middle point of the U-shaped metal wire and proceedingto the left and right ends, such that the cross-section of the U-shapedmetal wire is rotated from a horizontal position at the middle point ofthe U-shaped metal wire to an inclined position at each of the left andright ends, the inclined position having a predetermined angle.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure as well as a preferred mode of use, further objects, andadvantages of the present invention will be best understood by referringto the following detailed description of the preferred embodiments inconjunction with the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of an orthodontic deviceaccording to a first preferred embodiment of the present invention;

FIG. 2 is a side view and a top view of a U-shaped metal wire of theorthodontic device in the first preferred embodiment of the presentinvention;

FIG. 3 is an exploded front view of the orthodontic device in the firstpreferred embodiment of the present invention, wherein the orthodonticdevice is used to correct an upper jaw;

FIG. 4 is a front view of the orthodontic device in the first preferredembodiment of the present invention during correction of the upper jaw;

FIG. 5 is a front view of the orthodontic device in the first preferredembodiment of the present invention after the upper jaw is corrected;

FIG. 6 is an exploded front view of the orthodontic device in the firstpreferred embodiment of the present invention, wherein the orthodonticdevice is used to correct a lower jaw;

FIG. 7 is an exploded front view of an orthodontic device according to asecond preferred embodiment of the present invention, wherein theorthodontic device is used to correct an upper jaw as well as a lowerjaw;

FIG. 8 shows an orthodontic device according to a third preferredembodiment of the present invention, wherein the orthodontic device isused to correct an upper jaw; and

FIG. 9 is a front view and several sectional views of the U-shaped metalwire of the orthodontic device in the first preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 and FIG. 2, an orthodontic device 2 according to afirst preferred embodiment of the present invention includes a generallyU-shaped metal wire 21, a plurality of orthodontic brackets 22 cementedrespectively to the entire row of teeth 4 on an upper jaw 31 or a lowerjaw 32, and a plurality of fasteners for securing the U-shaped metalwire 21 in position to the plural orthodontic brackets 22 and therebypreventing the U-shaped metal wire 21 from falling off. In thisembodiment, the fasteners are a plurality of rubber bands 23 for settingthe U-shaped metal wire 21 in a groove 221 pre-formed on each of theorthodontic brackets 22 cemented to the row of teeth 4, so the U-shapedmetal wire 21 will not come off the grooves 211. In another embodimentwhich is not shown in the figures, the fasteners can also be covers ofself-ligation brackets in order to secure the U-shaped metal wire ontothe orthodontic brackets. The U-shaped metal wire 21 of the presentinvention has a left end 212 and a right end 211 which are at differentvertical heights with respect to a horizontal plane passing lengthwisethrough the U-shaped metal wire 21 at its middle point (with the leftend 212 being lower than the middle point, and the right end 211 higherthan the middle point, in the embodiment shown in FIG. 1). Consequently,the two ends 211, 212 are spaced apart by a vertical distance h (i.e.,difference of height). The vertical distance h must be greater than thevertical tilting height of the row of teeth to be corrected (i.e., thedifference of height between the left and right ends of the row ofteeth). Once the U-shaped metal wire 21 is installed on the pluralorthodontic brackets 22, which are cemented to and arranged linearly onthe teeth 4, as shown in FIG. 4, the U-shaped metal wire 21 is renderedinto a U-shaped curve which lies generally on the same plane andconforms to the positions of the orthodontic brackets 22. As a result,the U-shaped metal wire 21 generates a left-downward, right-upwardpushing force due to the resilience of the material of the U-shapedmetal wire 21. If the orthodontic device 2 is worn for a sufficientlylong time, the long-term left-downward, right-upward pushing forceexerted by the U-shaped metal wire 21 will cause the teeth 4 on theupper jaw 31 to displace gradually in a left-downward, right-upwardmanner, so that even occlusion between the teeth 4 on the upper jaw 31and the lower jaw 32 can be achieved while the slightly skew face isalso adjusted to a more desirable angle.

Reference is now made to FIGS. 2 through 5. As shown in FIG. 2, theorthodontic device 2 in the first preferred embodiment of the presentinvention defines a horizontal baseline 9 and a vertical baseline 8. TheU-shaped metal wire 21 is made of a resilient metal material and, asstated previously, has two ends 211, 212 which are positioned atdifferent vertical heights and spaced apart by the vertical distance h.Referring to FIG. 3 for a front view of the upper and lower jaws 31, 32,the right side 311 of the upper jaw 31 is slightly inclined toward thehorizontal baseline 9 such that malocclusion occurs, and consequently agap is formed (see FIG. 4), between the left side 312 of the upper jaw31 and the lower jaw 32. As the teeth 4 on the upper jaw 31 are slantedwith respect to the teeth 4 on the lower jaw 32, malocclusion betweenthe teeth 4 on the upper and lower jaws 31, 32 makes chewing difficult.

More specifically, taking the middle point A of the U-shaped metal wire21 as a reference point, and the horizontal baseline 9 as a referenceline, the right side of the U-shaped metal wire 21 is curved, startingfrom the middle point A, toward the upper law 31 (upward) by apredetermined angle θ1. Then, the end 211 is extended toward the rightside 311 of upper law 31 and is curved toward the lower jaw 32(downward) by a predetermined angle θ2. Similarly, the left side of theU-shaped metal wire 21 is curved, starting from the middle point A,toward the lower jaw 32 (downward) by the predetermined angle θ1, andthen the end 212 is extended toward the left side 322 and is curvedtoward the upper law 31 (upward) by the predetermined angle θ2.

Thus, the U-shaped metal wire 21 is in rotational symmetry with respectto the middle point A and has a 3-dimensional recumbent S shape in frontview. The predetermined curving angles θ1, θ2 are related to thevertical distance h between the two ends 211, 212 and hence related tothe magnitude of a resilient restoring force that the U-shaped metalwire 21 can generate. In the present embodiment, the resilient restoringforce of the U-shaped metal wire 21 is determined by three majorfactors: 1. the curving angles θ1, θ2; 2. the rigidity of the material;and 3. the thickness of the U-shaped metal wire 21, wherein the curvingangle θ1 preferably ranges from about 0° to 45° inclusive, and thecurving angle θ2 preferably ranges from about 15° to 90° inclusive.

Each tooth 4 has an outer surface 41 and a lingual surface 42. TheU-shaped metal wire 21 and the plural orthodontic brackets 22 on whichthe U-shaped metal wire 21 is installed are mounted on either the outersurfaces 41 or the lingual surfaces 42 of a row of teeth 4. Forinstance, if the orthodontic device 2 is to be installed on the outersurfaces 41 of the teeth 4, the orthodontic brackets 22 will be cementedto the outer surfaces 41 of the teeth 4 respectively. Taking the middlesection of the U-shaped metal wire 21 as the datum of the horizontalbaseline 9, the end 211 of the U-shaped metal wire 21 is locatedgenerally below the horizontal baseline 9 and is connected to theorthodontic brackets 22 on the teeth 4 adjacent to the molars at theback end of the right side 311 of the upper jaw 31. The other end 212,which is located above the horizontal baseline 9, is fixed in positionto the orthodontic brackets 22 on the teeth 4 adjacent to the molars atthe back end of the left side 312 of the upper jaw 31 and thus stressesthe U-shaped metal wire 21. The U-shaped metal wire 21 is secured, withthe rubber bands 23 (i.e., the fasteners) and in a section-by-sectionmanner, to the orthodontic brackets 22 cemented to the outer surfaces 41of the teeth 4 on the upper jaw 31 and is firmly set in the grooves 221.

As the vertical distance h between the two ends 211, 212 of the U-shapedmetal wire 21 is forced to decrease, the U-shaped metal wire 21generates a resilient restoring and yet twisting force thanks to theproperty of the metal material itself. The resilientrestoring-and-twisting force serves to adjust the row of teeth 4 on theupper jaw 31 or the lower jaw 32 to the normal tooth positions. Thegreater the vertical distance h between the two ends 211, 212 of theU-shaped metal wire 21 is, the stronger the resilient restoring forcegenerated by the U-shaped metal wire 21 will be, and the harder the twoends 211, 212 of the U-shaped metal wire 21 will spring back in the twoopposite directions of the vertical baseline 8 (i.e., an upwarddirection 81 and a downward direction 82).

It is understood that the vertical distance h between the two ends 211,212 of the U-shaped metal wire 21 can be properly set during themanufacturing process so as to produce U-shaped metal wires 21 ofdifferent levels of resilience for use in different orthodontictreatments. For instance, it is feasible to make the U-shaped metal wire21 in such a way that the end 212 is located below the horizontalbaseline 9 while the other end 211 is above the horizontal baseline 9;thus, the U-shaped metal wire 21 is suitable for treating a slantingupper jaw 31 whose left side 312 is closer to the horizontal baseline 9than the right side 311. In short, the relative positions of the twoends 211, 212 of the U-shaped metal wire 21 can be adjusted to provideorthodontic forces in different directions.

More specifically, once the U-shaped metal wire 21 is fixed in positionto the orthodontic brackets 22 on the outer surfaces 41 of the row ofteeth 4 on the upper jaw 31, thus forcing the vertical distance hbetween the two ends 211, 212 of the U-shaped metal wire 21 to reduce,the two ends 211, 212 of the U-shaped metal wire 21 are verticallypressed toward the horizontal baseline 9. As a result, referring to FIG.3 the end 211 of the U-shaped metal wire 21 generates a resilientrestoring force F1 acting in the upward direction 81 of the verticalbaseline 8 and thereby pushing the teeth 4 on the right side 311 of theupper jaw 31 (i.e., the side closer to the horizontal baseline 9) in theupward direction 81 of the vertical baseline 8. Meanwhile, the other end212 of the U-shaped metal wire 21 secured to the orthodontic brackets 22cemented to the teeth 4 on the left side 312 of the upper jaw 31generates another resilient restoring force F2, which acts in thedownward direction 82, so the teeth 4 on the left side 312 of the upperjaw 31, which are relatively far from the horizontal baseline 9, arepulled by the resilient restoring force F2 in the downward direction 82.When subjected to the two orthodontic forces F1, F2 of the U-shapedmetal wire 21 for a sufficient period of time, the upper jaw 31 as awhole is moved counterclockwise to the normal position, as shown in FIG.5. Thus, not only is normal occlusion between the upper jaw 31 and thelower jaw 32 achieved, but also the craniofacial appearance isesthetically enhanced.

The orthodontic device 2 of the first preferred embodiment of thepresent invention may also be installed alone on the teeth 4 on thelower jaw 32 and, as shown in FIG. 6, is applicable to the teeth 4 on alower jaw 32 whose left side 322 is inclined toward the horizontalbaseline 9 and therefore closer to the horizontal baseline 9 than theright side 321. After the U-shaped metal wire 21 is verticallycompressed, the resilient restoring force F2 generated by the end 212pushes the left side 322 of the lower jaw 32 in the downward direction82, and the resilient restoring force F1 generated by the other end 211of the U-shaped metal wire 21 pulls in the upward direction 81 the teeth4 on the right side 321 of the lower jaw 32, which are relatively farfrom the horizontal baseline 9. Thus, the U-shaped metal wire 21gradually brings the lower jaw 32 to a position capable of properocclusion. The orthodontic device 2 may also be installed on each of theupper and lower jaws 31, 32 so as to adjust the upper and lower jaws 31,32 to the proper positions at the same time.

The U-shaped metal wire 21 is made of stainless steel, iron, titanium,β-titanium, nickel titanium, clear material or a shape memory alloy. Theorthodontic brackets 22 are metal orthodontic brackets, ceramicorthodontic brackets, crystal orthodontic brackets, self-ligationbrackets or lingual orthodontic brackets.

The following paragraphs describe some other preferred embodiments ofthe present invention, wherein most of the elements and structures areidentical or similar to those in the previous embodiment and thereforeare not described repeatedly. While the same elements are identified bythe same names and the same reference numerals, those similar elementsare given the same names but are differentiated by an English lettersuffixed to the same reference numerals.

Please refer to FIG. 7 for a second preferred embodiment of the presentinvention, which is different from the first preferred embodiment inthat the end 211 a of the U-shaped metal wire 21 a of the orthodonticdevice 2 a is above the horizontal baseline 9 while the other end 212 ais below the horizontal baseline 9. Once the two ends 211 a, 212 a ofthe U-shaped metal wire 21 a are pressed vertically toward thehorizontal baseline 9, the end 211 a of the U-shaped metal wire 21 agenerates a resilient restoring force F3 acting in the downwarddirection 82 of the vertical baseline 8, and the other end 212 agenerates a resilient restoring force F4 acting in the upward direction81.

After the orthodontic device 2 a is installed on the upper jaw 31, theteeth 4 on the right side 311 of the upper jaw 31 (i.e., the siderelatively far from the horizontal baseline 9) are pulled in thedownward direction 82 of the vertical baseline 8 by the end 211 a of theU-shaped metal wire 21 a (or more specifically by the resilientrestoring force F3). Meantime, the teeth 4 on the left side 312 of theupper jaw 31, which are relatively close to the horizontal baseline 9,are pushed in the upward direction 81 by the other end 212 a (or morespecifically by the resilient restoring force F4).

The orthodontic device 2 a is equally applicable to the teeth 4 on alower jaw 32 whose right side 321 is inclined toward the horizontalbaseline 9 and hence closer to the horizontal baseline 9 than the leftside 322 (i.e., inclined in a direction opposite to that of the lowerjaw 32 in FIG. 6). In that case, the resilient restoring force F3exerted by the end 211 a of the U-shaped metal wire 21 a pushes theright side 321 of the lower jaw 32 in the downward direction 82, and theresilient restoring force F4 exerted by the end 212 a of the U-shapedmetal wire 21 a pulls the left side 322 of the lower jaw 32 in theupward direction 81, so as to adjust the lower jaw 32 to a positioncapable of proper occlusion.

A third preferred embodiment of the present invention is illustrated inFIG. 8 and differs from the first and second preferred embodiments inthat the orthodontic device 2 b includes lingual orthodontic brackets 22b for securing the U-shaped metal wire 21, wherein the lingualorthodontic brackets 22 b are installed on the lingual surfaces 42 ofthe row of teeth 4 on the upper jaw 31 or the lower jaw 32. Take anorthodontic treatment of the upper jaw 31 for example. The lingualorthodontic brackets 22 b are cemented to the lingual surfaces 42 of theteeth 4 on the upper law 31 respectively. Thus, the U-shaped metal wire21 (or the U-shaped metal wire 21 a in the second preferred embodiment)and the plural lingual orthodontic brackets 22 b on which the U-shapedmetal wire 21 (21 a) is installed are all located on the lingualsurfaces 42 of the teeth 4 and hidden from view from the outside. Inother words, the orthodontic device 2 b will not be seen on the outersurfaces 41 of the teeth 4, and therefore the outer appearance of theteeth 4 is not affected even under orthodontic treatment.

FIG. 9 is a front view and several sectional views of the U-shaped metalwire 21 in the first preferred embodiment of the present invention. Asshown in the drawing, the U-shaped metal wire 21 has a generallyrectangular cross-section. Furthermore, it can be clearly seen in FIG. 9that, in addition to the height difference between the two ends 211, 212of the U-shaped metal wire 21 that results from the predeterminedcurving angles θ1, θ2, the U-shaped metal wire 21 is twistedcontinuously in the same direction, starting from the middle point A andproceeding to the left end 212 and the right end 211. As a result, thecross-sections of the twisted left end 212 and the twisted right end 211of the U-shaped metal wire 21 are both inclined at a predetermined angleθ3, and because of the angle θ3 (or more specifically the twisting), theU-shaped metal wire 21 generates a linear torque, which not onlydetermines the torsion of the U-shaped metal wire 21 but also helpsincrease the resilience of the orthodontic device 2. Preferably, thepredetermined angle θ3 ranges from about 0° to 30° inclusive.

In a nutshell, the orthodontic device 2 of the present inventionincludes a resilient U-shaped metal wire 21 whose two ends 211, 212 areat different vertical heights and which is fixed in position, by meansof elastic bands 23, to a plurality of orthodontic brackets 22 cementedto the tooth surfaces. The height difference between the two ends 211,212 of the U-shaped metal wire 21 gives rise to a resilient restoringforce typical the metal material, and it is this resilient restoringforce that individually adjusts the row of teeth 4 on the upper jaw 31or the lower jaw 32 to the normal tooth positions. Consequently, notonly is proper occlusion between the teeth 4 on the upper and lower jaws31, 32 achievable, but also a slightly skew face can be adjusted to amore desirable angle.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. An orthodontic system, comprising a U-shapedmetal wire configured to be installed on a plurality of orthodonticbrackets cemented to a row of teeth, the U-shaped wire having first andsecond elongated sections connected by a curved section, with the firstand second elongated section having a first end and a second end,respectively, opposite from the curved section, wherein said U-shapedmetal wire has a middle point located at the middle between said firstand second ends, wherein a horizontal plane is defined along thelongitudinal length of the U-shaped wire, wherein said middle pointbeing located on said horizontal plane, and wherein the first end islocated at a vertical height lower than the horizontal plane while thesecond end is located at another vertical height higher than thehorizontal plane when the U-shaped wire is in its preformed uninstalledconfiguration, wherein after the U-shaped metal wire is installed on theplural orthodontic brackets cemented to the row of teeth, the first andsecond ends of the U-shaped metal wire are pressed vertically toward thehorizontal plane so as to generate a resilient restoring force for bothpushing and pulling the row of teeth on an upper jaw or a lower jaw andthereby adjusting the teeth from an inclined alignment to a horizontalalignment.
 2. The orthodontic system of claim 1, wherein the U-shapedmetal wire is made of a resilient metallic material, the resilientmetallic material being one of stainless steel, iron, titanium,β-titanium, nickel titanium, clear material and a shape memory alloy. 3.The orthodontic system of claim 1, wherein the U-shaped metal wire andthe plural orthodontic brackets on which the U-shaped metal wire isinstalled are provided on one of outer surfaces and lingual surfaces ofthe row of teeth.
 4. The orthodontic system of claim 1, wherein theU-shaped metal wire is fixed in position to the plural orthodonticbrackets by one of the following: a plurality of rubber bands and aplurality of covers of self-ligation brackets.
 5. The orthodontic systemof claim 3, wherein the orthodontic brackets are one of metalorthodontic brackets, ceramic orthodontic brackets, crystal orthodonticbrackets, self-ligation brackets and lingual orthodontic brackets, thelingual orthodontic brackets being cemented to the lingual surfaces ofthe teeth.
 6. The orthodontic system of claim 5, wherein the U-shapedmetal wire has a rectangular cross-section and is twisted continuouslyin the same direction, starting from the middle point of the U-shapedmetal wire and proceeding to the first and second ends, such that thecross-section of the U-shaped metal wire is rotated from a horizontalposition at the middle point of the U-shaped metal wire to an inclinedposition at each of the first and second ends, the inclined positionhaving a predetermined angle.
 7. The orthodontic system of claim 1,further including a plurality of fasteners for fixing the U-shaped metalwire in position to the plural orthodontic brackets and preventing theU-shaped metal wire from falling off.
 8. The orthodontic system of claim7, wherein the plurality of fasteners are chosen from the following: aplurality of rubber bands and a plurality of covers of self-ligationbrackets.